1. Field of the Invention
The present invention relates to a flat cable comprising a plurality of foil-like conductor strips having end portions connectable to terminals of a connector, and an insulating sheet in which said foil-like conductor strips are embedded in a manner such that the conductor strips are electrically isolated from each other.
2. Related Art Statement
The flat cable of kind mentioned in the preamble has been widely used in automobiles for connecting various electric parts. In case of manufacturing a flat cable, a metal foil is punched to form a plurality of foil-like conductor strips and then these conductor strips are sandwiched between insulating films made of synthetic resin such as PET to form a laminated structure.
Recently the number of electric parts has been increased and the circuit arrangement has become very complicated. Therefore, it has become difficult to establish an electrical connection between connectors by means of a single flat cable. For instance, in automobiles, plural kinds of flat cables having different structures have been used. This results in that a design of a circuit arrangement, manufacturing and cable fitting operation are liable to be complicated and the number of operation steps is increased so that an efficiency of manufacture is decreased. Therefore, a manufacturing cost is increased.
FIG. 1 is a plan view showing a circuit arrangement, in which a first connector 1 includes terminals a1, a2, a3, a4 and a5 aligned in this order and second connector 2 has terminals b5, b4, b1, b2 and b3 aligned in this order. It should be noted that terminals of the first and second connectors 1 and 2 having the same suffixes have to be connected to each other. That is to say, the terminal a1 of the first connector 1 should be connected to the terminal b1 of the second connector 2, the terminal a2 of the first connector 1 has to be connected to the terminal b2 of the second connector 2, and so on. If the corresponding terminals of the first and second connectors 1 and 2 are connected by means of a single flat cable Fc, the flat cable should have conductor strips c1-c5 some of which are crossed with each other. That is, the conductor strips c4 and c5 have to be crossed with the other conductors c1-c3 and further the conductor strips c4 and c5 should be crossed with each other as illustrated in FIG. 1.
The circuit arrangement shown in FIG. 1 is sometimes used in automobiles. In automobiles, a main harness is commonly used for different kinds of cars or at different portions of a car in order to reduce the number of different kinds of parts and a manufacturing cost. For instance, an inner door unit to be connected to the terminals a4 and a5 situates below the terminals b1-b3. In such a basic structure or specification, it is required to arrange the terminals b4 and b5 above the terminals b1-b3 in another kind of car or specification due to a layout within the inner door space.
In such a case, it is impossible to perform the connection between the connectors 1 and 2 by means of a single known flat cable, and at least two flat cables are required, one having a pattern for connecting the terminals a1, a2 and a3 to the terminals b1, b2 and b3, respectively and the other having a pattern for connecting the terminals a4 and a5 to the terminals b4 and b5, respectively.
In a known flat cable illustrated in FIG. 2, one end of the flat cable 6 includes end terminals connectable to terminals d1, d2, d3, d4, d5 and d6 of a first connector 3, and the other end of the flat cable has a first set of end terminals connectable to terminals e4 and e5 of a second connector 4 and a second set of end terminals connectable to terminals e3, e1, e2 and d6 of a third connector 5. Also in this case, foil-like conductor strips of the flat cable 6 have to be crossed with each other, so that it is practically difficult to perform the electrical connection between the first connector 3 and the second and third connectors 4 and 5 by means of a single flat cable. That is, in order to connect the first connector 3 to the second and third connectors 4 and 5, it is required no use a first flat cable connecting the terminals d4 and d5 of the first connector 3 to the terminals e4 and e5 of the second connector 4 and a second flat cable connecting the terminals d3, d1, d2 and d6 of the first connector 3 to the terminals e3, e1, e2 and e6 of the third connector 5.
As explained above, when an electric connection between connectors requires crossings of conductor strips, it is difficult to perform an electric connection by means of a single flat cable, so that a plurality of flat cables have to be used. Therefore, when a circuit arrangement becomes complicated, a larger number of flat cables of different structures are required. Therefore, the number of steps in designing is increased and the fitting operation of flat cables becomes cumbersome. Moreover, when the number of kinds of flat cables is increased, the number of blanking dies for manufacturing the flat cables is increased accordingly, and thus the manufacturing cost is increased.